84
AVERAGE VALUES IN A CANONICAL
or
|
(251)
|
Setting
in this equation, we get
|
|
and substituting this value, we have
|
|
or
|
(252)
|
If we differentiate equation (250) with respect to (which may represent any of the external coördinates), and write for the force , we get
|
|
or
|
(253)
|
Setting
in this equation, we get
|
|
Substituting this value, we have
|
(254)
|
or
|
(255)
|
Repeated applications of the principles expressed by equations (252) and (255) are perhaps best made in the particular cases. Yet we may write (252) in this form